A body frame for a conventional type motorcycle that includes a pivot part for supporting a swing arm that is provided on the body frame is known, for example, as set forth in JP No. 3436330.
FIGS. 2 to 4 of JP No. 3436330 will be described below.
A body frame 1 is provided with a main pipe 3 extending rearwardly and downwardly 1y from a head pipe 2 with a seat rail 4 extending rearwardly from the rear upside of the main pipe 3. A sub-pipe 7 is laid between a lower part of the main pipe 3 and the seat rail 4 with a pair of left and right reinforcements 13, 13 being attached to the rear and extending downwardly 1y of the main pipe 3. A cylindrical pivot part 8a is attached so that the main pipe 3 and the reinforcements 13, 13 are pierced with a rear shock absorber receiver 11 being attached to a connection of the main pipe 3 and the seat rail 4.
The above-mentioned reinforcements 13, 13 are welded to the main pipe 3, with the pivot part 8a being welded to the main pipe 3 and the reinforcements 13, 13 and the rear shock absorber receiver 11 also being welded to the main pipe 3 and the seat rail 4. The welded locations are increased and time for welding is also increases. In addition, as many parts are required, the weight and the cost is increased. Therefore, an enhancement in productivity, a lightening of the body frame and a reduction in the cost are desired.